* {
    margin: 0;
    padding: 0;
  }
  
  * {
    box-sizing: border-box;
  }
  
  *::after {
    box-sizing: border-box;
  }
  
  *::before {
    box-sizing: border-box;
  }
  
  #demo {
    word-break: break-all;
  }
  
  #div1 {
    position: fixed;
    left: 50%;
    transform: translateX(-50%);
    top: 20px;
  }
  
  #div1::before {
    content: "";
    display: block;
    position: absolute;
  }
  
  #div1::after {
    content: "";
    display: block;
    position: absolute;
  }
  
  @media (max-width: 500px) {
    #html {
      height: 50vh;
      overflow: auto;
    }
  
    #div1Wrapper {
      height: 50vh;
    }
  
    #div1 {
      position: relative;
      top: 0;
      right: 0;
    }
  }